Aristotle's biology 



vitality; and in a word, the whole genus of 

 plants, whilst it is devoid of life as compared 

 with an animal, is endowed with life as com- 

 pared with other corporeal entities. Indeed, as 

 we first remarked, there is observed in plants a 

 continuous scale of ascent towards the animal. 

 So in the sea, there are certain objects concern- 

 ing which one would be at a loss to determine 

 whether they be animal or vegetable. For in- 

 stance, certain of these objects [e.g. sponges] 

 are fairly rooted, and in several cases perish 

 if detached. . . . Indeed, broadly speaking, the 

 entire genus of testaceans has a resemblance to 

 vegetables, if they be contrasted with such 

 animals as are capable of progression. 



" In regard to sensibility, some animals give 

 no indication whatsoever of it, whilst others 

 indicate it but indistinctly. Further, the sub- 

 stance of some of these intermediate creatures 

 is fleshlike ... but the sponge is in every 

 respect like a vegetable. And so throughout 

 the entire animal scale there is a graduated 

 differentiation in amount of vitality and in 

 capacity for motion. 



" A similar statement holds good with regard 

 to habits of life. Thus of plants that spring 

 from seed the one function seems to be the 



[51] 



